56 lines
1.5 KiB
Python
56 lines
1.5 KiB
Python
import math
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from functools import lru_cache
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from typing import Optional
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@lru_cache(maxsize=1024)
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def varuint_to_bytes(value: int) -> bytes:
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if value <= 0x7F:
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return bytes([value])
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ret = bytes()
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while value:
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temp = value & 0x7F
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value >>= 7
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if value:
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ret += bytes([temp | 0x80])
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else:
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ret += bytes([temp])
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return ret
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@lru_cache(maxsize=1024)
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def bytes_to_varuint(value: bytes) -> Optional[int]:
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result = 0
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bitpos = 0
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for val in value:
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result |= (val & 0x7F) << bitpos
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if (val & 0x80) == 0:
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return result
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bitpos += 7
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return None
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def fix_float_single_double_conversion(value: float) -> float:
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"""Fix precision for single-precision floats and return what was probably
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meant as a float.
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In ESPHome we work with single-precision floats internally for performance.
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But python uses double-precision floats, and when protobuf reads the message
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it's auto-converted to a double (which is possible losslessly).
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Unfortunately the float representation of 0.1 converted to a double is not the
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double representation of 0.1, but 0.10000000149011612.
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This methods tries to round to the closest decimal value that a float of this
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magnitude can accurately represent.
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"""
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if value == 0 or not math.isfinite(value):
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return value
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abs_val = abs(value)
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# assume ~7 decimals of precision for floats to be safe
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l10 = math.ceil(math.log10(abs_val))
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prec = 7 - l10
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return round(value, prec)
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